Author(s): Fengwei Guo
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Abstract: The two criteria for ice induced steady state vibration (abbreviated as IISV in this paper) of vertical fixed structures are reanalysed. Using the two full scale structures (a concrete lighthouse and a monopod steel jacket platform), the damping criterion is calculated and it is found that the damping criterion provides an acceptable judgement of a given structure's susceptibility to IISV, even though the empirical coefficient in the equation is based on the negative damping hypothesis which is still doubted. Qualitative analysis indicates that the velocity criterion can be clearly explained by ice mechanics and structure dynamics. However, determining the amplitude of the velocity of the fluctuating structure at ice loading level is not straightforward, and strongly depends on the uncertainties of several parameters. In spite of this, for a given structure which is supposed to be susceptible to IISV, it is possible to estimate the magnitude of vibration. Using the results from several tests as supportive material, IISV is reanalysed from the viewpoint of ice breaking length. Finally, the phenomenon of IISV in transverse direction is discussed briefly.
Year: 2012